Special Report: Standards Rule: Infrastructure

In terms of standards compliance, the infrastructure space has had it easy, thanks to Ethernet. Can you imagine what life in the data center would be like if Token Ring, FDDI and ATM had gained significant market share? Fortunately, the graceful scalability of Mr. Metcalfe's protocol, which keeps getting faster (now up to 10 Gbps) without changing any of the other rules, has spared us from many interoperability woes.

We're not immune, of course--networking pros got a taste of what colleagues deal with when VoIP hit the scene. Until the IETF's SIP standard was embraced, VoIP phone systems were in danger of proprietary vendor lock-in. Other standards are making our complex infrastructures even easier to manage. Take the IEEE's 802.1ab LLDP (Logical Link Discovery Protocol) standard, which gives network devices the smarts to deliver topology information that can be used for mapping, troubleshooting, enabling E911 capabilities and more.

SIP

Session Initiation Protocol standard-based video and text communications are quickly becoming the focal point of all real-time communications. The SIP protocol works by setting up connections between peers--using servers to route calls--no matter where users are on an IP network. That means users can log in anywhere and bring their phone numbers with them. Sounds like a no-brainer, but not all vendors welcomed SIP with open product lines.

Most large VoIP service providers, such as Vonage, have used SIP from the beginning. Vonage supplies SIP-based adapters for existing phones, or customers can use SIP-based soft phones. On the enterprise side, however, some VoIP vendors have resisted giving third parties pieces of the revenue stream provided by proprietary phones. The tide is turning, though--Cisco recently joined market leaders Avaya and Nortel by supporting third-party SIP phones on its CallManager 5.0. This move sets the stage for widespread adoption and is a big boost for the SIP phone market, both soft and hard. And Microsoft, which has been a big SIP supporter, recently announced its own SIP phone initiative.

The SIP standard was conceived by Henning Schulzrinne in the mid-1990s, proposed as an Internet draft in 1999 (RFC 2543) and further solidified as RFC 3261 in June 2002. Seventeen SIPIT (Sip Interoperability Test Events) in the past seven years have given vendors ample opportunity to work out interoperability issues, and vendors serious about SIP have third-party testing programs. SIP has spawned hundreds of companies and thousands of products that are destined to forever change real-time communications for the better.» IETF standard

10 Gigabit Ethernet

The 10 Gigabit version of the venerable Ethernet standard emerged in the summer of 2003. While the original spec can run only on fiber, the CX4 standard, ratified in 2005, made it possible to run 10 Gig Ethernet using twin-ax cable at 15 meters, thus avoiding the optics that made upgrading so expensive. Last month, IEEE 802.3an was approved, providing a standard for running 10 Gigabit 100 meters over twisted-pair cabling--if you have TIA/EIA Cat 6a cabling installed. If you have plain Cat 6, you'll need to keep it under 55 meters.

When 10 Gigabit fiber ports were initially released, they cost between $50,000 and $100,000. Now you can get 10 Gigabit for a few thousand per port, with twisted pair ports expected to eventually drive the price down even further. Still, use caution when purchasing core switches and routers. For some, the connectivity between the modular cards and the backplane is limited, which decreases the density of ports per card that can achieve line-rate performance.

» IEEE standard» P802.3ak 10GBASE-CX4 Task Force

802.1ab LLDP

The IEEE's 802.1ab Logical Link Discovery Protocol standard greatly facilitates management and troubleshooting of network devices. For example, one switch can collect port-level information--including number, duplexity and speed settings, device descriptions and current status--on every other connected device. This functionality is valuable for mapping the topology of a switched network. And although 802.1ab-collected info is stored in SNMP MIBs and can be retrieved by SNMP management stations, 802.1ab goes a step beyond SNMP by advertising to and collecting information from directly connected devices.

The 802.1ab standard uses TLV (Type, Length, Value) frames that are predefined and extensible. One such extension, LLDP-MED (TIA/ANSI 1057), makes use of optional TLVs to pass information from VoIP phones to switch ports about QoS and duplexity; this info can be stored in the switches' MIBs and compared for mismatches. Switches can store location-specific information and dynamically configure phones with the info to help deal with E911, for example. Mitel and Avaya have phones that support the standard.

Cisco's CDP (Cisco Discovery Protocol) has some of 802.1ab's capabilities, but CDP is proprietary, as are similar protocols developed by other vendors, including Extreme Networks and Foundry Networks. Thus far, Hewlett-Packard/ProCurve and Extreme have released switches that take advantage of 802.1ab. The standard was approved in April 2005, so there's no excuse for other vendors not to add support in upcoming releases.» IEEE standard

Peter Morrissey, an NWC contributing editor, can be reached at [email protected].